ABSTRACT
Ion-pair chromatography (IPC) is similar to reversed-phase-high-performance liquid chromatography (RP-HPLC), as reversed-phase stationary phases are used in both cases. It can be used effectively for the speciation of cations, anions, and neutral species simultaneously. A counterion is added in the mobile phase in RP-HPLC, and the technique is termed IPC. The mobile phase used was tetrabutylammonium hydroxide, with detection by ultraviolet and amperometric devices. The formation of micelles occurs in aqueous mobile phase when the concentration of the counterions exceeds a critical micelle concentration. The micellar phase acts as a stationary phase, while the aqueous phase acts as the mobile phase in micellar electrokinetic. In chiral chromatography, the mobile or stationary phase contains chiral molecules, which are used for the resolution of enantiomers. A hybrid technique between HPLC and capillary electro was developed in 1990 and is called capillary electrochromatography. Supercritical fluids have been used as mobile phases in liquid chromatography, and the modality is known as supercritical fluid chromatography.
